Nonquaternary carbon-4 piperidinol esters and ethers and arylpiperidines have been synthesized for study of their action on the central nervous system. Nine compounds displayed analgesic activity in the codeine-morphine range in the mouse hot-plate assay. The antinociceptive activity of 1-methyl-4-piperidinol, 2,4,5-trimethylpyrrole-3-carboxylate trifluoroacetic acid salt was not antagonized by naloxone in the mouse tail-flick test. In general, the more active piperindinol esters showed no morphine-like physical dependence capacity in monkeys, acting neither as typical narcotic agonists nor antagonists. In rat brain homogenates in vitro, they displayed marginal to no binding to the opiate receptor. In qualitative Hansch-type structure-activity correlation, aromatic esters exhibited plus Es - pi substitutent effects. In conjunction with these studies, pyrrole carboxylic and pyrrole acetic acids are being evaluated as potential antiinflammatory analgesics by prostaglandin synthetase inhibition and by other standard assay systems.